CRISPR Cas9 and Gene Editing Explained

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CRISPR
CRISPR

CRISPR and the CRISPR Associated system are powerful gene-editing technologies.

For the scientists, the genes and its related fields have been an area of interests for research for a number of years. They have found a lot of therapies and treatments where modern technologies are used to cure various diseases as well as preventive treatments. The DNA(Deoxyribonucleic acid) is the system of the human body with the help of which one can study the genes and decipher many things that can be used to treat various diseases that happen to an individual. Among these studies, the leading one is CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) that have originated before few decades. CRISPR was first described by Osaka University researcher Yoshizumi Ishino and his associates in the year 1987. They accidentally duplicated part of a CRISPR together with the “iap” gene which was the original interest.

See: A beautiful Infographic on CRISPR and Gene Editing

Genome editing is a group of methods that gives researchers the ability to modify the DNA of an organism. These technologies let genetic substance to be added, detached, or transformed at specific locations in the gene. Several methods to genome editing have been advanced. The latest one is recognized as CRISPR-Cas9.

crispr-cas9-mode-of-action
CRISPR Cas9 – Mode of Action. Image Source: Wikipedia

Cas9 (or “CRISPR-associated protein 9“) is an enzyme that uses CRISPR DNA sequences as a guide to recognize and cleave specific strands of DNA that exactly match given CRISPR sequence, it is so precise in matching DNA that Cas9 can be called as a GPS locator of DNA. Cas9 enzymes together with CRISPR sequences form the basis of a technology known as CRISPR-Cas9 that can be used to edit genes within organisms.

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CRISPR technology is a modest yet influential tool for excision genes. It lets researchers alter DNA arrangements and modify gene function effortlessly. Its many possible applications include modifying genetic defects, giving and averting the spread of diseases and refining crops.

This system has produced a lot of enthusiasm among the researchers and scientists because it is quicker, inexpensive, more precise, and more well-organized than other prevailing methods for genome editing.

Growing CRISPR Research
Credit: WebOfKnowledge
CRISPR-Cas9 from Nature

CRISPR-Cas9 was adapted from a naturally happening gene editing process in bacteria. Whenever viruses attack bacteria they inject there own code of DNA into the bacteria and if the bacteria survives this attack, it stores the virus’s DNA in a DNA archive called CRISPR. When the same virus or any virus of the same strain attacks the bacteria again, the bacteria quickly produces an RNA from the stored DNA and uses the Cas-9 protein to scan through to find the exact match of virus DNA. If it does find a match, it removes that DNA protecting the bacteria from the virus.

The CRISPR-Cas9 scheme works likewise in the lab. Examiners create a small portion of RNA with a short “guide” arrangement that attributes (binds) to a precise target arrangement of DNA in a gene. The RNA also muddles to the Cas9 enzyme. As in microbes, the adapted RNA is used to identify the DNA arrangement, and the Cas9 enzyme punctures the DNA at the battered location. Even though Cas9 is the enzyme that is used most frequently, certain other enzymes like Cpf1 (CRISPR-associated endonuclease in Prevotella and Francisella 1) can also be used. Once the DNA is cut, investigators use the cell’s DNA repair gear to add or delete pieces of inherited material or to make variations to the DNA by substituting prevailing section with a tailored DNA sequence.

dna
The human DNA model takes on a double helix shape. Source: www.pixabay.com

Gene editing is of inordinate importance in the inhibition and treatment of the human ailment. Presently, most study on genome editing is done to comprehend diseases using cells and animal models. Researchers are still at work to define whether this method is harmless and operative for use in people.

Use of CRISPR in different fields

Now let us look into some other potential uses of CRISPR which can be revolutionary:

1) Genetically editing crop seeds for higher yields and higher nutrition: Researchers are doing various experiments with crop seeds and CRISPR. They are trying to develop resistance against diseases in crops. Companies have been licensing CRISPR technology to develop new varieties of crops.

CRISPR crop research data
(Credit: WebOfKnowledge)

2) Using CRISPR to prevent and cure deadly diseases: It is being discovered in the investigation on a wide diversity of ailments, as well as single-gene complaints such as cystic fibrosis, haemophilia, and sickle cell disease. It can also prevent more complex diseases, such as HIV, Zika, Cancer, Heart Disease, Mental illness. Apart from prevention, scientists claim that we can even cure diseases like HIV. We can even develop effective antibiotics (which are becoming ineffective day by day) against an increasing number of superbugs.

3) We could alter an entire species: CRISPR has the potential to alter a complete species. This concept is called Gene Drive. Generally, whenever organisms mate there is a 50-50 chance to pass a particular gene but using CRISPR we can make a particular gene to pass with nearly 100 percent probability. This can be pretty beneficial if we use it properly, for example, we can totally prevent Malaria by genetically editing mosquito.

CRISPR could alter entire species
Regulating gene drives, Biotechnology journal, Javier Zarracina; Oye et al. 2014

4) Genetically edited Babies: Researchers are trying to give birth to genetically edited babies which could have amazing qualities. Not going into the depths, but once imagine how could it be, you can give birth to a baby with any quality you want, literally any quality!!! (News: Russian Scientist Says 5 Couples Have Agreed to Gene-Editing Babies to Avoid Deafness)

Moral concerns do ascend during the editing of genome, using technologies such as this one, is put to use to make changes in human genes. Most of these variations are known with gene editing and are incomplete to somatic cells, which are cells other than egg and sperm cells. These deviations affect only definite tissues and are not conceded from one age group to the next. However, alterations made to genes in egg or sperm cells or the genes of an embryo could be distributed to future groups. Embryo genome and germline cell editing are developed with numerous ethical trials, including the probabilities if same can be permitted to use this technology to improve normal human traits like height or intelligence. Centred on apprehensions about integrity and wellbeing, germline cell and embryo gene editing are at present illegal in many nations.

CRISPR Controversies

Though CRISPR has a lot of potential, it also has a lot of controversies around it. Many researchers claim that CRISPR could cause extensive mutation and gene damage which could not be easily detected.

A Chinese scientist named He Jiankui created the first ever genetically edited twin babies. He also edited one more baby with the twins. The Chinese government stated that he has violated Chinese rules and has avoided supervision, faked an ethical review, and used potentially unsafe and ineffective gene editing methods on the children. This created a lot of controversies around CRISPR in early 2019.

Even after that, there have been reports from various parts of the world describing controversial and unethical CRISPR research. There are reports saying that researchers have edited the genes of healthy embryos which is illegal and have created controversies.

In between all this, we have also got bio-hackers who can create potentially harmful micro-organisms using CRISPR as this technology is available to anyone and is easier compared to other gene editing technologies. So, we have to monitor CRISPR usage and watch potential bio-hackers to save humanity from some gene edited deadly microbes.

CRISPR has the potential to make completely altered human beings which can be dangerous in many ways. So, there is are many rules in force against the use of CRISPR in almost all countries. But still, there is a possibility that someone could misuse this technology.

Advantages of CRISPR over other Gene Editing Methods

Questionably, the most imperative rewards of CRISPR-Cas9 over other genome editing technologies is its uncomplicatedness and effectiveness. To give a good comparison if old methods are like maps then CRISPR is like a GPS system. CRISPR/Cas9 is way faster and decreases the time required to perform a gene edit to a few days from a few months or even years. CRISPR gene editing is way cheaper than other gene editing technologies.

Risks of gene editing?

Gene treatment has some probable risks. Even though CRISPR is said to be easy, it is not that easy to replace the targeted gene only. It is not like we just catch a thread cut it and tie with something else, gene editing is complex. There is a very good chance that we can make a mistake and lead to unwanted mutations (BREAKING: CRISPR Could Be Causing Extensive Mutations And Genetic Damage After All)

This method presents the subsequent risks

  1. An unwanted reaction in the immune system might occur.
  2. Wrong cells may get targeted if we are editing specific cells in grown-up organisms.
  3. There is a possibility of infection.
  4. The new segments may get inserted in the wrong spot leading to unwanted and dangerous changes.

Conclusion

There is a lot of buzz around CRISPR and gene editing and if used properly can give good results otherwise can be harmful to humanity. There must be National and International Organisations strictly monitoring gene editing research and any trial of biohacking must be strictly punished. Things apart, let us hope that CRISPR gets established and we get fruits of it early in the form of disease prevention, cure, good crops etc.

An Infographic on CRISPR and Gene Editing

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CRISPR Cas9 and Gene Editing Explained

 

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